Evaluation of nuclear reaction cross-sections and fragment yields in carbon beams using the SHIELD-HIT Monte Carlo code. Comparison with experiments

Abstract

In light ion therapy, the knowledge of the spectra of both primary and secondary particles in the target volume is needed in order to accurately describe the treatment. The transport of ions in matter is complex and comprises both atomic and nuclear processes involving primary and secondary ions produced in the cascade of events. One of the critical issues in the simulation of ion transport is the modeling of inelastic nuclear reaction processes, in which projectile nuclei interact with target nuclei and give rise to nuclear fragments. In the Monte Carlo code SHIELD-HIT, inelastic nuclear reactions are described by the Many Stage Dynamical Model (MSDM), which includes models for the different stages of the interaction process. In this work, the capability of SHIELD-HIT to simulate the nuclear fragmentation of carbon ions in tissue-like materials was studied. The value of the parameter κ, which determines the so-called freeze-out volume in the Fermi break-up stage of the nuclear interaction process, was adjusted in order to achieve better agreement with experimental data. In this paper, results are shown both with the default value κ = 1 and the modified value κ = 10 which resulted in the best overall agreement. Comparisons with published experimental data were made in terms of total and partial charge-changing cross-sections generated by the MSDM, as well as integral and differential fragment yields simulated by SHIELD-HIT in intermediate and thick water targets irradiated with a beam of 400 MeV u(-1) (12)C ions. Better agreement with the experimental data was in general obtained with the modified parameter value (κ = 10), both on the level of partial charge-changing cross-sections and fragment yields.

Microdosimetry of proton and carbon ions

“…24,25 The nuclear interaction cross sections used in the code and the obtained dose profiles in tissue-like media for proton and heavier ion beams have been shown to be in good agreement with available experimental data. 18,26,27 The 1 H and 12 C ions with initial energies 160 MeV and 290 MeV/u, respectively, were transported through a cylindrical water phantom of 10 cm in diameter and 30 cm in length. The cylinder was divided into slabs of 1 mm thickness.…”

Decomposition of the absorbed dose by LET in tissue-equivalent materials within the SHIELD-HIT transport code

“…In the simulation we took into account all the generations of secondary particles produced in inelastic nuclear interactions, as well as elastic nuclear scattering, fluctuations of ionization losses (according to the Vavilov-Landau theory), and multiple Coulomb scattering (Moliere theory). A more detailed description of capabilities of the SHIELD-HIT code can be found in the papers [1][2][3][4][5][6][7] cited above.…”

“…Since the measurements of LET spectra are labor-consuming, especially if the spectra of separate secondary fragments are measured [11], the computational approach is desirable. The model of nuclear fragmentation, which is used in the SHIELD-HIT code, was improved and well benchmarked in previous studies against experimental data and other Monte Carlo codes (see, e.g., [4][5][6] and references therein). For example, one may observe a reasonable agreement between the present results of Bragg curves and those of the given results in [1] and references therein.…”

“…The model of nuclear fragmentation, which is used in the SHIELD-HIT code, was improved and well benchmarked in previous studies against experimental data and other Monte Carlo codes (see e.g. [4][5][6] and references therein).…”

“…The SHIELDHIT transport code (http://www.inr.ru/shield/) has been repeatedly used for modeling of the interaction of therapeutic beams of hadrons and light nuclei with tissue equivalent materials (see, for example, [1][2][3][4][5][6][7]). Previously, we presented the simulation of decomposition of the absorbed dose by LET in water * Correspondence: rogul@selcuk.edu.tr for 16 O +8 beams within SHIELD-HIT code [8].…”